Seismo Blog

Updates and dispatches from the PNSN

October 3, 2012

by John Vidale

Altarock Energy Corp., a Seattle-based renewable energy development company, is planning to start on October 8th to inject water for circulating in the hot rocks near Newberry Volcano. The operation is on the outer flanks of the volcano, five miles west of the most recent volcanic activity.

The goal this fall is to (1) inject water deep into ground, (2) let the ground heat the water, (3) bring the hot water back to the surface, (4) measure the hot water's flow rate and temperature to determine how much electricity could be generated.

We expect to see numerous small earthquakes during the weeks this fall of testing this system, and later when the system starts to operate for actual energy extraction.

This particular arrangement, an Enhanced Geothermal System (EGS, descriptive video), is designed to circulate particularly deep in the ground, and with low-pressure fluid flow, in order to minimize escape of the fluids and minimize the number and magnitude of induced and triggered earthquakes. The blog on Altarock's website is replete with details.

We at the PNSN, in league with our partners at the Cascade Volcano Observatory (CVO), have precise monitoring of the Newberry Volcano, as reported here. Seismograms in the region can be monitored here.

One detail about jargon - triggered earthquakes are pushed over the edge by a geophysical disturbance but the causative stress was already in the ground, induced earthquakes are powered by the disturbance, in other words, for induced events, the stress that powered the event was not present until the disturbance.

The injection of pressurized fluid is expected to induce the formation of zillions of tiny cracks to allow the circulating fluid to easily flow, and may trigger some small earthquakes that release the natural stresses pent up in the ground.